Apollo Shift Register Is Discrete

June 19, 2021 by Al Williams 10 Comments

We’re unabashed fans of [Ken Shirriff] here at Hackaday, and his latest post about an Apollo-era transistorized shift register doesn’t disappoint. Of course, nowadays a 16-bit shift register is nothing special. But in 1965, this piece of Apollo test hardware weighed five pounds and likely cost at least one engineer’s salary in the day, if not more.

The incredible complexity of the the Apollo spacecraft required NASA to develop a sophisticated digital system that would allow remote operators to execute tests and examine results from control rooms miles away from the launch pad.

This “Computer Buffer Unit” was used to hold commands for the main computer since a remote operator could not use the DSKY to enter commands directly. Externally the box looks like a piece of military hardware, and on the inside has six circuit boards stacked like the pages of a book. To combat Florida’s notoriously damp conditions, the enclosure included a desiccant bag and a way to fill the device with nitrogen. A humidity indicator warned when it was time to change the bag.

There is a lot more in the post, so if you are interested in unusual construction techniques that were probably the precursor to integrated circuits, diode transistor logic, or just think old space hardware is cool, you’ll enjoy a peek inside this unusual piece of gear. Be sure to check out some of [Ken]’s previous examinations, from tiny circuits to big computers.

Turning GameCube & N64 Pads Into MIDI Controllers

June 19, 2021 by Lewin Day 2 Comments

It’s fair to say that the Nintendo 64 and GameCube both had the most unique controllers of their respective console generations. The latter’s gamepads are still in high demand today as the Smash Bros. community continues to favor its traditional control scheme. However, both controllers can easily be repurposed for musical means, thanks to work by [po8aster].

The project comes in two forms – the GC MIDI Controller and the N64 MIDI Controller, respectively. Each uses an Arduino Pro Micro to run the show, a logic level converter, and [NicoHood’s] Nintendo library to communicate with the controllers. From there, controller inputs are mapped to MIDI signals, and pumped out over traditional or USB MIDI.

Both versions come complete with a synth mode and drum mode, in order to allow the user to effectively play melodies or percussion. There’s also a special mapping for playing drums using the Donkey Konga Bongo controller with the GameCube version. For those eager to buy a working unit rather than building their own, they’re available for purchase on [po8aster’s] website.

It’s a fun repurposing of video game hardware to musical ends, and we’re sure there’s a few chiptune bands out there that would love to perform with such a setup. We’ve seen other great MIDI hacks on Nintendo hardware before, from the circuit-bent SNES visualizer to the MIDI synthesizer Game Boy Advance. Video after the break.

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IPod HiFi Gains New High Notes

June 19, 2021 by Jenny List 1 Comment

The iPod HiFi was a stereo speaker add-on produced by Apple in the mid-2000s for their iPod range, a $300-plus speaker cabinet with twin drivers per channel, an iPod dock, aux, and TOSLINK interfaces. It’s caught the eye of [Jake], in particular one posted on Reddit that had an extra set of tweeters to improve the HiFi’s lackluster treble. The question was that it might have been an Apple prototype, but lacking his own [Jake] set out to replicate it.

The job he’s done is to a high quality. The baffle has first 3D scanned, and then recesses were milled out of it so the tweeters could be press-fit in. He’s driving them through a simple LC crossover circuit taken from the speaker drive, and reports himself happy with the result.

Unfortunately, we still don’t know whether or not the Reddit original was an Apple prototype or not. We’d be inclined to say it isn’t and praise the skills of the modder who put the tweeters in, but in case it might be we’d point to something that could deliver some clues. The iPod HiFi didn’t use a passive crossover, instead it had a DSP and active crossover, driving four class D amplifiers. If you find one with tweeters and they’re driven from the DSP through an extra pair of amplifiers then put it on eBay as a “RARE BARN FIND APPLE PROTOTYPE!” and make a fortune, otherwise simply sit back and enjoy the extra treble a previous owner gave it.

Of course, some people baulked at the price tag of the Apple speaker, and made their own.

1700 Regulatory Approvals Revoked In South Korea

June 19, 2021 by Chris Lott 40 Comments

For the first time since its inception, the Korea Communications Commission this week revoked the regulatory approvals of 1,696 telecommunications devices from 378 companies, both foreign and domestic. Those companies must recall unsold inventory from the shelves, and prove conformity of existing products already sold. In addition, the companies may not submit new applications for these items for one year. It’s not clear what would happen to already-sold equipment if the manufacturer is unable to prove conformity as requested — perhaps a recall? Caught up in this are CCTV products, networking equipment, Bluetooth speakers, and drones from companies like Huawei, DJI, and even Samsung.

The heart of the issue are what’s known as Mutual Recognition Agreements (MRAs) between countries to officially recognize of each other’s certification testing laboratories (or Conformity Assessment Bodies, CAB, in the lingo of the industry). Currently ten countries (USA, Canada, Mexico, UK, Israel, Japan, Korea, Singapore, Vietnam, and Australia), the 27 member states of the EU, Taiwan and Hong Kong all have MRAs with each other. Based on these MRAs, a Korean manufacturer could have a product tested by a laboratory in Israel, for example, and all would be kosher with the KCC.

At the center of attention is the Bay Area Compliance Laboratories (BACL), established in 1996 and headquartered in Sunnyvale, California. BACL has laboratories all over the world (USA, Taiwan, Hong Kong, Vietnam, and mainland China). Except for those in mainland China, all BACL laboratories are acceptable per the MRAs. The KCC received a tip last year that some compliance test reports for some products might be defective.

A six-month investigation in cooperation with the US National Institute of Standards and Technology (NIST) resulted in the announcement this week. Korean companies, 378 of them to be exact, had submitted test reports from BACL Sunnyvale which appeared to be appropriate. But on further investigation, it was learned that the actual testing was done by BACL laboratories in mainland China and only the reports were prepared in Sunnyvale.

It’s not clear whether these companies were knowingly playing fast and loose with the rules, whether BACL was complicit, if it was just a misunderstanding of the intricacies of the regulations and MRAs, or a combination of all three. Regardless, the KCC said that intent doesn’t matter according the their rules. It also has not been suggested that the products themselves are problematic, nor has anyone suggested that BACL’s Chinese laboratories performed slipshod work — rather, the KCC says it has no choice but to proceed with the revocation based on the applicable laws.

Vacuum Tube Magic Comes To The 741

June 19, 2021 by Jenny List 41 Comments

Some of you may remember a recent project that featured on these pages, a 555 timer reproduced using vacuum tubes. Its creator [Usagi Electric] was left at loose ends while waiting for a fresh PCB revision of the 555 to be delivered, so set about creating a new vacuum tube model of a popular chip, this time the ubiquitous 741 op-amp. (Video, embedded below.)

The circuit is fairly straightforward, using six small pentodes. The first two are a long-tailed pair as might be expected, followed by two gain stages, then a final gain stage feeding a cathode follower with feedback. It’s neatly built on a PCB with IC-style “pins” made from more PCB material, then put in a huge replication of an IC socket on a wooden baseboard.

The result is an op-amp, but not necessarily a good one. He looks at the AC performance instead of the DC even though it’s a fully DC-coupled circuit, and finds that while it performs as expected in a classic op-amp circuit it still differs from the ideal at higher gain. The frequency response is poor too, something he rectifies by replacing the feedback capacitor with a smaller value. Sadly he doesn’t look at its common mode performance, though we’d expect that without close matching of the tubes it might leave something to be desired.

It’s obvious that this project would never be selected as an op-amp given the quality of even the cheapest silicon op-amp in comparison. But its value is in a novelty, a talking point, and maybe a chance to learn about op-amps. For that, we like it.

We covered the vacuum tube 555 when details of it emerged, but if op-amps are your bag we’ve looked at a simple one very closely indeed.

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Growing Up With Computers

June 19, 2021 by Elliot Williams 78 Comments

My son is growing up with computers. He’s in first grade, and had to list all of the things that he knows how to do with them. The list included things like mousing around, drawing ghosts with the paint program, and — sign of the times — muting and unmuting the microphone when he’s in teleconferences. Oh yeah, and typing emojis. He loves emojis.

When I was just about his age, I was also getting into computers. But home computers back then were in their early years as well. And if I look back, I’ve been getting more sophisticated about computers at just about the same pace that they’ve been getting more sophisticated themselves. I was grade school during the prime of the BASIC computers — the age of the Apple II and the C64. I was in high school for the dawn of the first Macs and the Amiga. By college, the Pentiums’ insane computational abilities just started to match my needs for them to solve numerical differential equations. And in grad school, the rise of the overclockable multi-cores and GPUs powered me right on through a simulation-heavy dissertation.

When I was a kid, they were playthings, and as a grownup, they’re powerful tools. Because of this, computers have never been intimidating. I grew up with computers.

But back to my son. I don’t know if it’s desirable, or even possible, to pretend that computers aren’t immensely complex for the sake of a first grader — he’d see right through the lie anyway. But when is the right age to teach kids about voice recognition and artificial neural networks? It’s a given that we’ll have to teach him some kind of “social media competence” but that’s not really about computers any more than learning how to use Word was about computers back in my day. Consuming versus creating, tweeting versus hacking. Y’know?

Of course every generation has its own path. Hackers older than me were already in high-school or college when it became possible to build your own computer, and they did. Younger hackers grew up with the Internet, which obviously has its advantages. Those older than me made the computers, and those younger have always lived in a world where the computer is mature and taken for granted. But folks about my age, we grew up with computers.

Tell Time The Cistercian Way

June 19, 2021 by Jenny List 10 Comments

It’s rare for the fields of the engineer and the mediaevalist to coincide, but there’s a clock project bringing the two fields together. The Cistercian monastic order used an intriguing number system from the 13th century onwards that could represent any four-digit number as a series of radicals expressed in the four corners of a single composite symbol, and it’s this number system that’s used by the clock to render the full range of 24 hour time on a large 5×7 LED matrix mounted on a wooden base.

Behind the scenes is an Arduino and a DS3231 real-time clock, and all the code can be found in a handy GitHub repository. There’s even a PCB from everyone’s favourite vendor of purple PCBs, The result is certainly an interesting clock that makes the break from the usual binary and Nixie timepieces with some style. It also provides an introduction to this fascinating but obscure numerical system, in the event that any of us might have missed the one other such clock that has made it to these pages.